Ganoderma lucidum, the general name for Ganoderma lucidum karst and Ganoderma japonicrn L. loyd, belongs to Polyporaceae family, Ganodelma genus. With the effect of strengthening healthy, it is considered as a treasure in Shen Nong's Herbal. As a Chinese traditional precious medicinal herb used for thousands of years, Ganoderma lucidum has a very high medical value. After decades of modern pharmacology studies by research institutions, it is confirmed that Ganoderma lucidum has remarkable therapeutic effects in enhancing human immunity, regulating blood glucose, controlling blood pressure, assisting tumor radiotherapy and chemotherapy, protecting liver, promoting sleep and so on. Medical certificates that Ganoderma lucidum, Ganoderma sinense and Coriolus versicolor have the highest medicinal value. Recent years, chemical elements and clinical studies on Ganoderma fungi are more and more. The effects of flavonoids thereof are in many ways. Flavonoids are strong antioxidants which can effectively clear up the oxygen free radical in organism. The ability of flavonoids to prevent oxidation is ten times more than the vitamin E, which can prevent cell degradation and aging, and cancer occurring. Natural flavonoids compounds mostly exist in the form of glycosides, different flavonoid glycosides can be formed as the kinds, numbers, connecting locations and connecting modes of sugars are different. In twentieth Century late eighties, flavonoids were noticed as a health product for the first time by the international medical community. Experiments demonstrated that flavonoids of Ganoderma lucidum can improve blood circulation, lower cholesterol, improve the symptoms of cardiovascular disease, lower blood sugar by 26% and tri-Glycerides by 39%, stable collagen, and play good roles in retinopathy and blood capillary fragility caused by diabetic.
At present, more than 10 kinds of flavonoids compounds have been isolated from Ganoderma lucidum, including flavones, flavonols, flavanones and so on. However, the production of flavonoids in Ganoderma lucidum becomes the limiting factor for inhibiting its application. In natural word, the wild Ganoderma lucidum is very rare and cannot meet people's needs. It is an effect method to produce active pharmaceutical ingredients of Ganoderma lucidum by fluid fermentation, because this method has the advantages of short production cycle, less labor and small impact by the external environment. Studies at home and abroad are mainly about the culturing of Ganoderma lucidum mycelium to produce active pharmaceutical ingredients, and the industrial applications are mainly concentrate on the technical aspects such as fermentation condition, product extract and separation, etc., and the total fermentation level is low.
Chinese patent CN1264743A (application No. 00111953.2) discloses a liquid fermentation method for preparing ganoderic polysaccharide and ganoderic acid. In the method, the bacterial strain Ganoderma lucidum (Leyss exFr.) Karst. is used as its microbe, and the aerobic liquid fermenting process, the aerobic liquid fermentation-static liquid culture method, or static liquid culture process is used for production ganoderic exopolysaccharide, ganoderic intracellular polysaccharide and ganoderic acid. Its advantages are high gandoric acid content up to 2.8 mg/100 mg, high total polysaccharide content up to 2.34 g/L. The method needs static culturing to induce synthesizing production. The fermentation period is long, and the total fermentation time including liquid aerobic fermentation and static culturing is more than 20 days. The overall producing efficiency is low, which could not meet the need of modern industrial fermentation and production. There is no report about the high yielding liquid fermentation and extraction technologies of Ganoderma lucidum flavonoids component, which even more limits its development of industrial application.
Expansin is a new type of protein species found in plant cell walls in the recent years. Expansin is first obtained by separating and purifying the elongation field of cucumber hypocotyl. It has been proved that expansin is also existing in the cell wall of oat coleoptile, Trichosanthes kirilowii root tip, tomato, strawberry, arabidopsis, paddy, cotton fibrin, corn, soybean, etc, and is considered existing in various dicotyledonous and monocotyledonous plant cell walls. It is considered that expansin is related to promoting the cell physiological growth, affecting the physiological growth processes such as vegetative growth, morphogenesis, pollination and fertilization, and fruit softening, etc. Experiments about cell wall recombination have shown that expansin has the function of recovering the thermal inactivated cell wall in vitro to extend, which is different with other enzyme proteins for cell wall found formerly. It is supposed that expansin can regulate physiological activities such as acid-dependent cell wall extension and stress relaxation by breaking the hydrogen bonds between the cell wall polymers, and may be an important regulatory factor for physiological regulation and cell wall extension process in the period of plant growth. However, there is yet no unambiguous study conclusion of the function mechanism of expansin at home and abroad. Currently there is no report at home and abroad about that the expansin is applied in liquid fermentation of Ganoderma lucidum for increasing the yield of flavonoids ingredients.